DE 25 48 408 [GB 1,514,104] describes a tap changer that consists of a load changeover switch, tap selector and preselector and in which a polarity switch is provided below the tap selector coaxially therewith. The polarity switch consists of an insulating cylinder arranged below the tap selector. A plurality of plug contacts is on the inner wall of the insulating cylinder on a helix and a respective rod-shaped porcelain resistor is inserted into each two of these plug contacts.
DE 29 31 000 describes a tap changer in which a cylindrical load changeover switch is carried by a tap switch head and in which, in addition, a support—that is matched to the cylindrical shape of the tap changer—for polarity resistors is outside the circumference of the load changeover switch. According to a first alternative, the support consists of at least two insulating-material rings of the same circumference that are around the load changeover switch at an axial spacing, wherein rod-shaped polarity resistors extending in the direction of the cylinder wall of the load changeover switch are insertable into plug contacts seated at the insulating-material rings. According to a second alternative, the support is constructed as a switch part of insulating material that in circumference covers approximately ¼ to ⅓ of the circumference of the tap changer and supports the polarity resistors at its inner side.
DE 36 44 206 describes a multi-phase load selector for tapped transformers with a reverser arranged laterally of the load selector, wherein the reverser extends over the entire height of the load selector and is constructed as a segment of a tube. Several rod-shaped polarity resistors connected into a series circuit are provided on both sides of the tube segment in a zigzag line through the wall.
DE 89 14 598 U1 describes a fastener for polarity resistors at tap changer of tapped transformers, which fastener serves for fastening of the resistors on or to insulating-material cylinders, segments or other insulating fastening means and at the same time for electrical connection of each end of the rod-shaped polarity resistors with an electrical potential, wherein the fastener consists integrally of an electrically conductive material and has an outer, approximately spherical profile, in which a cylindrical opening extends, the diameter of the opening being slightly larger than the shank diameter of the polarity resistors to be fixed, wherein provided perpendicularly to the longitudinal axis of this opening in cut-outs of the fastener are presser bodies that are at a defined angle relative to one another and are guided to be radially movable and that are urged into the interior of the opening by means of compression springs, and wherein a threaded bore, into which a bolt for fastening and electrical contact-making can be screwed, is present in the fastener and radially penetrates the wall thereof.